Question: Solve for $x$ and $y$ using substitution. ${-3x-y = -11}$ ${y = 4x-10}$
Since $y$ has already been solved for, substitute $4x-10$ for $y$ in the first equation. ${-3x - }{(4x-10)}{= -11}$ Simplify and solve for $x$ $-3x-4x + 10 = -11$ $-7x+10 = -11$ $-7x+10{-10} = -11{-10}$ $-7x = -21$ $\dfrac{-7x}{{-7}} = \dfrac{-21}{{-7}}$ ${x = 3}$ Now that you know ${x = 3}$ , plug it back into $\thinspace {y = 4x-10}\thinspace$ to find $y$ ${y = 4}{(3)}{ - 10}$ $y = 12 - 10$ $y = 2$ You can also plug ${x = 3}$ into $\thinspace {-3x-y = -11}\thinspace$ and get the same answer for $y$ : ${-3}{(3)}{ - y = -11}$ ${y = 2}$